Electric cooker.



F. C. PERKINS.

ELECTRIC COOKER. APPLICATION FILED ocT.1o,1911.

Patented Mar. 25, 1913.

2 SHEETS-SHEET l.

F. G. PERKINS.

ELECTRIC GOOKER.

APPLIGATION FILED 00T.10,1911.

L,56,933. Patented Mar. 25, 1913.

2 SHEETS-SHEET 2.

FRANK C. PERKINS, OF BUFFALO, NEW YORK.

ELECTRIC COOKER.

Specication of Letters Patent.

Patented Mar. 25. 1913.

.Applicationfiled October 10, 1911. Serial No. 653,846.y

To all whom, t may concern.'

Be it known that I, FRANK C. PERKINS, a citizen of the United States,residing at Buffalo, in the county of Erie and State of New York, haveinvented new and useful Improvements in Electric Cookers, of whichthefollowing is a specification.

This invention has for its object the production of a high grade as wellas simple, cheap and ericie'nt means of heat insulating the inner liningfrom the outer wall of a metal electric cooker, to prevent the loss byconduction through the joints, which. has heretofore been the greatestloss of heat, in metal cookers, the radiation through a section from theinner lining to the outer shell having been small with ordinary meansot' insulation as compared to the great escape from lining and bottomthrough metal contact joints to the inner shell; also the eiii.

cient, cheap and simple application of electric heating to such cookers,whereby food may be'cooked or material heated to temperatures up to 300or 4:00' degrees Fahrenheit or thereabout with comparatively small lossin heat.

It is well known that most cookers utilize hot plates of iron or soapstone which are heated by gas, coal or oil flame and placed within thecooking chamber, the utensils with or without a heated body of waterbeing in the same chamber as said hot plates. The large amount of heatabsorbed by the water and hot plate is slowly given up to the food to becooked, 'when the whole is inclosed-'in a chamber well insulated withasbestos, mineral wool or regranulated cork to prevent the heat fromescaping to the outside of the cooker. e

My invention provides for the vplacing of the hot plates of iron,composition or soap stone permanently 1n the base, side walls or cover,or any or all of same or of one or more sections of a built up sectionalcooker, each hot plate section being heated over a gas or other burneron a stove or by means of alcohol lamps supported by a wire frame underasingle cooker section or under several sectionswhih are stackedtogether, the necessary air/ for supporting combustion lpassing betweenthe sections which are held apart by the wire frames or guards.

In the ordinary cooker, the heat is all rs't absorbed by the water orhot plates heated by a flame and then given o to the food during thenight orA other time of day while. in my invention electric heat isapplied to the side walls and bottom of a cooker or section ot'l samewhich. allows the heat to be applied quickly and retained by hot plates,or the electricheat may be applied slowly without hot plates and only asmall amount of heat electrically used continuously for aconsiderablelength of time or throughout the night, so that the food ishot and ready for service in the morning. With the ordinary cooker notonly must outside heat be applied to boil the water in the first placebut the food, While thoroughly cooked, must still be reheated a triflebefore serving.. In this ap` plication of electric heat all hot platesmay be done away with if desired, because the wall or base -wiring forproducing the electric heat is at roasting or high temperature so as toLetl'ect quick cooking; baking or browning of roast meats. One of thesewindings only is utilized for producing a high temperature of shortduration while for long Vcontinuous heat at very low temperatlbre bothside and base windings are placedin series'.

If thermostatio electric control is desired in the base of the cooker acombined electric heater, condenser and thermostat may 'be lemployed,holding the' temperature at any point .desired by the adjustment of ascrew or equivalent device at the center of the base.

In the accompanying drawings consisting of 2 sheets :-.-Figure l is avertical section of a cooker embodying my improvements in the mostelaborate form.' Fig. 2 is a similar view showing a cooker of simplerlform containing my improvements. '.Fig. 3 is a` perspective view showingmy invention' embodied in an electric baking oven or roaster. Fig. 4- isa diagrammatic-view of the wiring of the thermostatic electric heaterand condenserforming. part of my invention. Fig. 6 is a fragmentaryvertical section, on an enlarged scale, showing one of the" means fordetachablyconnectingtwo adacent sections of a sectional iireless cooker.Fig. 7 is a diagrammatic plan View of the preferred manner lo arrangingthe' of enameled ware.

.y a cylindrical 'upright outer wall l, a cylindrical uprightinner wall2 having its upper edge Hush with the upper edge ot the out-er wallwhile its lower edge stops short of the lower edge of the outer wall, ahorizontal louter bottom 3 connected with the lower edge of the outerwall, a horizontal inner bottom 4 connected'with the lower edge of theinner wall, and a ring 5 connecting the upper edges of the outer andinner Walls, said Walls, bottoms and ring being constructed ofearthenware, enamelware, asbestos board or sheet met-al, such asaluminum or` galvanized iron. Y.

. The cover preferably4 comprises an upright cylindrical outer wall 6, ahorizontal top 7 connected with the upper edge of the outer wall,' and ahorizontal bottom 8 connectedvwith the lower edge of the outer wall,

said wall and top being constructed of earthenware, .asbestos board orsheet metal,

- such as aluminum or galvanizedl iron and Aso the bottom ot sheet metalsuch as aluminum.

The bottom and outer wall of each vessel and the top and outer wall ofthe cover constitute the jackets or shells of these body members, andthe bottom of the cover and the inner wall and bottom of each vesselconstitute the linings of thesebody members.

The severalvessels and the cover are preferably interlocked by means ofan annular tongue, bead or rib 9 formed on the underside ot the bottomof each of these members except the lowermost adjacent tothe pe.`l

ripheny thereof and engaging with an annular groove 1'() in the ring 'ofthe member next below the same, thereby producing a practically airtight joint' between the several members for confining the heat withinthe vessels. The space within each l .of the vessels and the coverconstituting the body members of the cooker is packed or loaded with afilling 11 of heat insulating material such as asbestos, mineral wool orregranulated cork.

'For the purpose of reducing the loss of heat by conduction from theinner walls and bottoms of the vessels and the bottom of the cover tothe outer walls ofv these members when the latter' are of sheet metal,insulating means are provided which prei-'erably comprise a strip 12 ofasbestos securedlby silicate of soda, asbestos-cement or other adhesivebetween the interlocking marginal flanges of the outer wall and the topring of each vessel, alsobetween the 1narginal interlocking flanges onthe outer wall and bottom of each vessel, alsobetween the interlockingmarginal flanges of the outer wall and bottom of the cover, and alsobetween the marginal interlocking flanges ot' the outer wall andl top ofthe cover.

The several body members of'the cooker may be detachably connected byany suitable means, for instance bythe means which are shown in thedrawings and which con` sist of two loops 21, 22 pivoted on adjacentbody members and a clamping lever 23 pivoted on one ofthe loopsand'engaging with the other loop, as shown in Fig.

For the purpose of avoiding the necessity of handling hot plates as isthe case when thel same are made separate from the body of the cookerand placed within the latter after being heated, such plates may bepermanently built in the space between the outer jacket and the innershell of one or morefof the body members, as shown for instance in Fig.l, in which a hot plate 24 is `embedded in the insulating fillingbetween the inner and outer bottomsl of the uppermost vessel. By meansof this construction a saving'of room within the cooking space ofthe'cooker is effected and also separate handling of the hot plates isavoided, it being only necessary to place the cooker sectionoontainingthe hot plate over a burner or on a stove and after the plate in eachsection is suficiently hot the food to be cooked is inclosed within thecooking space either withl or without the utensils or dishes forcontaining the same.

In order to still further conserve or retain the heat within thecompartments of the cooker so as 4to utilize the same with the betterel'ect incooking the food the lowermost vessel may be insulated from itssupport, for instance by resting the underside of the lowermost vesselon a .heatI and electricity insulating pad 25 of asbestos or similarmaterial which is supported by a base 26 of metal or other suitablematerial. To still further save the heat within the cooker and preventradiation of the same to the outer atmosphere, the cookermay be inclosedby a hood 27 having sides and top closed and theopening at'its lowerendclosed by resting its lower edge on the insulating pad 25. By thismeans a temperature of 350 degrees Fahrenheit, may be maintained withinthe compartments of the cooker, thus saving a great amount of energy.

To permit of electrically heating the cooker each of its members may beprovided with suitable heating wires which are adapted to conduct acurrentl of electricity. As shown invFig'. 1, an electric heatin coil orwinding 28 of wire is arranged horlzontally between the topand bottom ofthe cover while each of the Vessels is provided with a lower horizontalheating coil or windlng i of wire 29 between the inner and outer botablyconnected in series, as shown in Fig.

5, and the same are provided at the outer Wall with three terminals 33,34, 35, one of which is connected with the corresponding ends of theupper and lower coils while the other two are connected with the oppolsite extremities of the upper and lower coils so that the same may beconnected with the source `of electricity in a manner to conduct thecurrent Ithrough both the upper and lower coils lor through either ofthe same alone according to the heat desired.

If desired, each of the electric heating coils may be wound or laidbetween sheets 36 of 4 aslfeetos which latter in turn are embedded in aslab 37 of material which is high in specific heat, such as concrete, ora mixture of sand and asbestos-cement which slab can take the place ofiron or soap stone hotplates. This electrically heated slab may bearranged between the lining and jacket of one vof the body members andin Contact with the bottom, as shown' for instance between the bottomsof the intermediate vessel, in Fig. l or thesame may be in actualcontact with the lining of the body members', as shown in the cover anduppermost vessel of Figs. 1 and 6. In thisI last mentioned constructionthe concrete or asbestos and-"sand composite forms a cement whichadheres to the aluminum lining of .the cover and vvesseland holds thewire Coils in place thereon. lThe com osition vof the -slab must be ofhigh speci c heat such as concrete containing a largery proportion ofsilica or quartz, asis found in 80 percent.

quartz sand. Asbestos cement may also .be used as the composition forthe slab, inasmuch as the same is a good binder and elecv tr1c insulatorAand is reproof.

If desired, the electric wires or `coils may be omitted vfrom the slab,Iwhen the latter is secured to the lining of a body member in which case,thesame serves the sole pur- "pose of storing the heat Which\has beenimparted to it and gives' the'same of to the articles to be cooked in avessel; thereby taking the place of ordinary hot plates of iron :or soapstone but leaving `more roomr within the cooker for victuals to becooked. When the slabs of the cooker sections are unprovided withelectric wires the same/'may be heated by placing the same overa fire oriame, so that the heat strikes the aluminum linin which conducts thesame quickly to the s ab and the latter in turn absorbs the same rapidlyowing to its having the form of a thin layer. The asbestos-sand-cementor concrete composite material thus heated weighs only about half asmuch as the iron hot plates, on account of the high specific heat, .19of the quartz sand being nearly double that of iron which is only about.11 at the same time the specific heat of aluminum used for the liningis more than double or .23, water being 1.00. It will thus be seen thatthe aluminum lining absorbs twice as much heat, and saves more thandouble its weight over iron hot plate storage, in addiweight one halffor the insulation over the latter, thus allowing a greater heat storageweight, in the composite material without increasing the weight of thedevice. The result of this construction does away with outer hot platesin whole or in part, with little or no greater weight than the other vconstruction using heavier insulation material.

In case no heat storage is desired when electrically heated, the wiringis applied to the wall and bottomof the aluminum lining with anasbestos' sheet interposed between the wires and the lining and with orwithoutv cement of silicate of soda or asbestos cement for attachingsame firmly to the aluminum lining.

If very high temperatures yare used in heating, the conductors areliable to burn the regranulated cork and to prevent this a layer ofmineral wool, sheet asbestos or cel-` lular asbestos may be interposedbetween the 'wires and the cork insulation which is /packed in the wall,the latterbeing next to i the/outer wall.

If\desired, the electric heater may be so organized that itis controlledthermostaticaly and alsoy serves as a condenser. As shown in Fig. 4, andbetween the bottom of the lowermost vessel or cooker section in Fig. 1,this combined thermostatic Velectric heater and condenser comprises alower horizontal disk 38 .of zinc which serves as a base provided at itsperiphery with an edge 39, an

upper horizontal disk 40 of galvanized iron having a depending iiange 4lwhichr is connected with the edge 39 of the base, a condenser y42constructed of a tin plate of one polarity and arranged between the topand bottom plates 40, 38, forming theother pole., an electric heatingunit 290 having preferably the" form of a wire-coil or Winding andarranged between the bottom plate 38 and the los vided with a platinumpointwhich is adapted to engage with a platinum contact 47 securedcentrally tothe center condenser plate.' The 'heating coil has one ofits ends connected with the condenser plate and the other end with aninsulated binding post or connection 20 on the bottom plate. The

screw 45 forms one terminal of the electric circuit of this thermostaticheat lcontroller and condenser and' the platinum contact 47.

` the other terminal.

- As the electric heat is produced by the passage of the electriccurrent through the coil 290 the Zinc lower plate and the galvanizediron upper plate both expand but the zinc plate expands faster than thegalvanized iron plate causing the zinc plate to bulge downwardly at thecenter. When the heat has reached a predetermined degree a-t which thescrew 45 has been set the bulging of the Zinc plate causes the terminalscrew to be disengaged from' the contact 47, thereby breaking theelectric circuit through the coil 290 and causing the temperature tofall. When the zinc plate owing to the reduced temperature hascontracted sufliciently to bring the contact screw 45 in engagement withthe terminal 47 the electric circuit is again restored and heat isresumed until the temperature rises above the normal or the degree atwhich the thermostatie switch has been set when the circuit will beagain automatically broken. In this manner the 'heat is alwaysmaintained at practically yuniform temperature.

j For the purpose of rendering the screw 45 accessible when it isdesired to adjust the same the outer bottom of the vessel containingthis thermostatic 'controlling device is provided with an opening 48through which said screw may be reached either by hand or by means ofatool for turning the same.

rIhe-action of the condenseris to reduce to a minimum or eliminateentirely the sparking at the platinum contacts of the thermostatadjusting screw point contact and the platinum rivet or disk contact.The center tinplate acts as one of t-he poles of the condenser, say thepositive pole, and the inclosing zinc and galvanized'iron platesfastened together at the periphery thereof form the other or negativepole. When the contact is broken at the adjusting screw platinum pointthe. spark is eliminated orv reduced to a minimum by the electricitycharging these positive and negative platesf -in the same manner asin'the tin foil) condenser of an induction coil and for the same purpose,viz: to'reduce the spark.

thermostatic sealing device preferably comprises a supplemental plug orcover 49 which is constructed of aluminum, zinc, or other high expandingmetal alloy which may have a downwardly-tapering edge whichy lits acorrespondingly shaped seat on a ring secured in the upper end of theopening of a vessel, as shown in the uppermost vessel of the sectionalcooker illustrated in Figs. l and 6. The ring 50 may be constructed ofiron or similar metal and the joint between the same and the plug ispreferably ground. Upon heating the plug the same expands faster thanits seat ring, thereby forming a tight joint between the same andeectually confining the heat within the chamber. of the sealing plug maybe effected by the electric heating coils above or by means 'of a hotplate 51 of iron or soap stone which may be removably inserted in apocket 52 in the upper side of the sealing plug, as shown in Fig. l.

To permit of removing the plug it is only necessary to first cool thesame either by cutting oif the electric current or pouring cold Waterinto the pocket of the plug which causes the same to contract and loosenthe joint between the same and the seat ring. Substantially the sameeffect is produced by the heating of the outer bottom of each uppervessel which engages with the top of the next lower vessel for closingthe latter, inasmuch as the bottom when heated electrically, orotherwiseexpands and forms a tight joint' with its seat on the nextlower vessel. j

If it is desired to heat the vessel with alcohol lamp when on `a picnicwhere electricity or other heating means are not available, this may beconveniently done by placing the articles to be cooked in the uppermostvessel and supporting a lamp 53 under this vessel by 'means .of a rack54 which is arranged bet-Ween the bottom ofthe uppermost vessel and thetop of the next lower vessel, as shown in Fig. l.

In case the food to be cooked requires an unusual amount of heat the,lpot 19 holding the food within the cooking chamber has its cover 55dished downwardly to form a recess '56 in the same which receives a hotplate 57, as shown in Fig. 1. This form of cover and pot also permits ofetfectually sealing this pot.

In Fig. 2 is shown a cooker which contains but one .double Wall Vessel57 and a. cover 58, the space between the walls of the vessel containingan insulating filler or packing and a thermostatic electric heater Theheating and condenser 17 and .the vspace between the walls of the coveralso .containing an insu.

lating packing and an electric heater 16 similar to that shown in Fig.1.

The sealing plug 59 in the construction shown in Fig. 2, engagesdirectly with the ring 60 which connects the outer and inner verticalwalls 0f this vessel and this plug is 'suspended by an annular ange 61on the perlphery thereof resting on the top ring 60 of the' vessel.

The form of cooker shown in Fig. 3 is*v for supporting thel bake pans 65or other utensils in a horizontal position, the electric heating meansbeing substantially like those shown in Fig. 1.

In the enameled ware electric roaster shown in Fig. 8, the inner andouter walls 66 and 67 ofthe vessel are stamped from a single sheet ofmetal and the silicate or 4 enamel glazing on the same is continuousonflts inner and outer sides and the electric h eatin wires 68 aresecured to the underslde o the inner wall or lining over asbestoscemented with silicate of soda. The

lower edge ofthe oiiter wall of the vessel iss -is preferably secured.to a base 69, a cover 70 is employed for closing the top of the vessel,and a hood 71 is placed over the vessel and cover and supported on thebase for conserving the heat.

I claim 'as my invention:

A 1.1An electric cooker, having a body composed 0f a plurality `0fmembers each of- 1911 which is provided with ajacket, a lining, anlnsulation between the marginal parts of said jacket and lining andaninsulating support for said body.

2. An electric cooker comprisin a metal cooking chamber, an insulatingpa for supporting said chamber, and a hood inclosing said chamber.

porting said chamber, a base which carries said pad, and ahood'inclosing said chamber and resting at the edge of its lower openingon said pad.

4. An electric cooker comprisin a double walled chamber, and athermostatically controlled electric heater arranged between the walls of said chamber and comprising two connected plates of di'erentiallyexpansible material, an electric heating coil arranged between'saidplates and having one end connected with the source of current supply, afixed termina] connected with Athe other end of said coil, and a movableelectric terminal coperating with the ixed terminal and mounted on oneof said expansible plates.

5. An electric cooker comprising a double walled chamber and athermostatically controlled electric heater arranged between the wallsof said chamber and comprising two connecrzted plates of `differentiallyexpansible material, an electric heating coil arranged betweenl saidplates'and having one end conixed terminal connected with the other endof said coil, a movable electric terminal cooperating with the fixedterminal and mounted" on one of said eXpansible plates, and ya condenserplate arranged between said expansible plates and carrying said 4fixedcontact or terminal.

Witness my hand this 7th day of October,

. FRANK C. PERKINS.

Witnesses: 4

' E. M. GRAHAM,

ANNA HEIGIs.

3. An electric cooker comprising ametal' cooking chamber, an insulatingpad for supnected with the source of current supply, a

